Abstract Objectives: The study aimed to investigate the absorption and fluorescence properties of 4MPDC in various solvents and understand the influence of solute-solvent interactions on its spectral characteristics. Methods: The study employed solvatochromic methods, including Lippert-Mataga polarity function, Reichardt's microscopic solvent polarity parameter, and Kamlet and Catalan's multiple linear regression techniques. Gaussian software 16W with B3LYP/6-311G basis set was used to estimate electric dipole moments. Findings: Hydrogen bonding interactions dominate dielectric interactions in pure solvents. The excited state dipole moment is greater than the ground state dipole moment. The compound's HOMO and LUMO energies indicate chemical activity and molecular interactions. The HOMO energy is -0.21624 eV, the LUMO energy is -0.07912 eV, resulting in a HOMO-LUMO energy gap (ΔE) of 0.13712 eV. The excited state has an intramolecular charge transfer (ICT) character. Polar solvents alter the fluorescence properties of coumarin. Quantum Yield (Φf ): Predicted 0.28–0.84. Lifetime (τf ): ~1–5 ns. Novelty: The study highlights the significant role of solute-solvent interactions in influencing the photophysical properties of 4MPDC, providing insights into its potential applications. The molecule has biomedical applications and can be used in optoelectronic devices. Keywords: DFT structure, LUMO and HOMO, Absorption spectra, Fluorescence spectra, UV-VIS spectra, IR spectra, Dipole moments, Polarizability, Fluorescence quantum yield, Lifetime
Lingappa et al. (Fri,) studied this question.